I was looking this summer for a door lock system for a residential building with 3 apartments, which could also be extended in the future for the 4th one.
In the same time I was planning to implement an Asterisk based home PBX which would allow internal communication between the three apartments and also provide access to the outside world trough a PSTN line.
Why not mixing the two of them together?
So, little by little I started to build the hypothesis.
Already having:
- wifi SOHO router D-link Dir 320 running DD-WRT v24 mini usb
- one Asus SOHO 8 port switch without management
- FXO line from Romtelecom
First obstacle would be the PSTN gateway. Looking for an affordable SOHO equipment (the enterprise gateways like Mediatrix are way over my budged even If i buy them second hand) I found to Linksys SPA3102 to be close to my needs.
In conjunction I should also decide what phone I should use as a door phone. Looking on the internet, I thought that I've found exactly what I needed: ITS Telecom Door Openers, but the price disseminated me a little bit :( 700$ is way to much!!!
Therefore I went up thinking that Linksys SPA3102 has a spare FXS port, where I could connect one analog phone - from the cost perspective that would be perfect to be placed at the door.
Question is: how can one trigger the door lock with an analog phone connected to a SIP gateway?? The answer I found lately is DTMF. So I have decided to use a DTMF decoder like in the following example: http://www.scribd.com/doc/29306350/HOME-AUTOMATION-USING-PHONE-DTMF-TOUCH-TONE-modified-version. Now initial data is completed and I should start working.
I' ll keep you guys posted.
To be continued...
